The invention relates to containers for cargo such as bulk waste material, especially intermodal containers, and more particularly concerns a container having a closure mechanism with a panel mounted for displacement perpendicular to the plane of the closure, in addition to being mounted for hinging or sliding, to facilitate sealing.
Bulk materials, finished products, parts and components, and also waste materials are frequently transported in large containers that preferably seal tightly when closed. Although there are a number of standard sizes, particularly for intermodal containers, a typical container is approximately twenty feet long, six to eight feet wide and four to twelve feet deep.
Such containers advantageously are openable at the top to facilitate loading and unloading. U.S. Pat. No. 5,533,643xe2x80x94Kruzick, for example, discloses a box-like container having a movable top panel or lid that covers an opening occupying a large portion of the top. The lid can be displaced to either side of the container on a roll track, and upended. When closed or moved over the opening, clamps permit the lid and the roll track to be pulled down against the container against spring pressure, for compressing a resilient seal around the perimeter of the opening.
Another container structure is disclosed in U.S. Pat. No. 5,639,129xe2x80x94Lindley, wherein the top of the container is open but an end door provides an alternative path for loading, as well as dumping of the contents by tipping the container at an appropriate site to discharge the contents through the end. The door defines one full end of the container and is attached to the ends of the opposite side walls on a vertical hinge at the end of one side wall, and a latching mechanism at the other side wall.
Containers as described may be subject to very rough handling and must be of a sturdy construction. The two containers cited above are structured much like dumpsters in that they can be pulled onto a carrying vehicle having a ramp or tiltable flat bed, or urged onto a vehicle by backing a tilting support under a container held at a stop. Such containers are frequently pushed about. They may be handled with fork trucks and are sometimes dropped or at least set down very hard in handling. Materials may be dumped violently into the containers when loading. During normal use, damage and misalignment can occur, particularly in the lids and doors, and their associated seals. Damage to the lids, doors or their seals can result in leakage from the container, and ingress of water.
Containers may be designed with standardized fittings that enable alternative ship, rail and road transport. The fittings are positioned to be engaged by standard locating and fixing pins or hooks of a container in a staging area or on a vehicle placed at a defined position. To support the container when moved from a vehicle to the ground, and vice-versa, the container may have slide runners or rails along the bottom or roll-off hoist structures such as undercarriage wheels. For applying the necessary lateral force via a cable, chain or grasper, a post or hook can be secured to the frame or undercarriage of the container, to receive a hook or cable bight, etc.
Whether the container is structured to be moved in one way or another, moving the container, as well as loading and unloading the container, may generate considerable internal force and stress. The container is most capable of resisting forces that might deform the container if the walls and joints of the container are continuous and well braced. The container is vulnerable to deformation to the extent that closures are provided because the closures are discontinuities in the structure of the container. With respect to loading and unloading, the closure areas are also vulnerable to being struck with falling material or bumped and banged by loading and unloading manipulators.
Where a container closure encompasses a structural wall of the container such as the end wall in the Lindley container mentioned above, the closure must be as heavy and durable as a structural wall, and should be mounted to provide secure mechanical connections of the closure panel with the container structures adjacent to each opening. The container closure also needs to maintain an adequate seal, for example a watertight seal. Often, the objects of providing a heavy closure are inconsistent with the need to provide a good seal.
In the case of a container used for potentially hazardous waste, it is particularly important that the door and lid be sealed in a manner that will not permit accidental seepage of the contents. However, for contents that are not generally considered hazardous, a seal may also be important to prevent water from gaining ingress and damaging the contents. For some materials, water in the container may leach chemical agents from the contents, and the leachate can be a problem.
Large waste containers preferably are transportable by rail if desired, where maximum container height limits are set by federal regulations. Height regulations also apply to over-the-road transport. In addition to the foregoing considerations or mechanical strength and effective sealing, it is desirable that any top lid cover the entire top opening in one piece. It is desirable that the lid and the mechanism for supporting the container lid project above the container as little as possible. Another advantageous aspect would be to provide a lid mechanism that can be handled by a single person.
Containers with end door closures are dumped by opening a door at one end of the waste container, and raising the other end of the container so that the contents slide through the open door by gravity. Dumping containers often have a horizontal hinge at the top of a pivoting door panel, which structure is useful in that the hinge mounting structurally supports the container by fixing the distance between the sidewalls adjacent to the door. However, such a door interferes with access for loading and unloading through the end. In the Lindley container, the hinge axis is vertical. The door is hinged to one of the container sidewalls and is latched to the other. This arrangement places substantial stress on the hinge-side container sidewall. The weight of the door is cantilevered. When the door is pivoted to or near to the closed position, the weight of the door produces a force tending to sway the container hinge axis inwardly and cause the door to droop across the opening. As the door is swung open or closed, the direction of the swaying force varies, stressing the side wall. When the door is closed, it is necessary for the latch side to engage securely to support the weight of the door.
Moreover, the relative movement of a vertically hinged door panel wears the seals. Releasing the latching engagement of the door can result in damage to the seal as the disengaged door panel drops downwardly around a point at the bottom of the door hinge axis. As the door drops at the latch side, the portions of the door and container defining the seal grind over one another in the plane of the end opening. Such grinding wear on the seal is difficult to avoid. Even if the vertically hinged door does not droop at all, the motion of the door panel is rotational about its hinge axis. Rotation around the hinge axis translates into at least a slight relative displacement in the plane of the opening, namely displacement of the door panel relative to a seal strip on the ends of the container side walls (or vice versa) as the seal is compressed. The relative motion is perpendicular to the opening only at the precise point at which the door panel is at the nominal closed position, typically perpendicular to the container side wall. The seal is engaged by the door panel over an arc of the door panel as the door panel contacts and then compresses the seal, which grinds at the seal.
There is a need for a simple, durable and reliable mechanism for permitting the cover or lid of a large container to be easily manipulated between a locked and sealed position and an open position clear of the corresponding container opening, while optimizing sealing. There is also a need for a relatively durable end closure that can provide a reliable seal in a variety of conditions and which is easily used without normal operation causing undue wear on the seal.
According to an inventive aspect, a container that comprises a plurality of sidewalls, a top and a bottom, is provided with a sealing closure in at least one of the walls or portion of the top, comprising a door or panel that is mounted for movement perpendicularly inwardly and outwardly of the closure plane, for moving between a closed-but-unsealed position and a closed-and-sealed position, and additionally is provided with a gross mounting structure for moving the door panel more generally from the closed-but-unsealed position to an open position substantially clear of the opening.
In one embodiment of the invention, a container is provided that comprises sidewalls, a bottom wall, and a top wall defining an opening. A movable lid that is sized to cover and sealingly close the opening is positioned upon the top wall. At least two guides are positoned on the top wall adjacent to the top opening, spaced apart from one another and movable between a first position and a second position. A carriage is mounted on the lid which rides upon the guides wherein the guides and the carriage cooperate to enable the lid to move between (i) a closed and substantiallly sealed position corresponding to the first position of the guides and (ii) a closed and substantially unsealed position corresponding to the second position of the guides wherein the lid is free to be slid upon the guides. The lid can slide or roll on the guides, and preferably is carried on rollers that are captive in the guides, above and below, and permit the lid to be moved to either side and upended to open the container. Preferably, the guides are displaceable either pulled down onto container seals or lifted from the seals for movement without interference with or from the seals.
In another embodiments of the invention, a container is provided that comprises a plurality of walls bounding a volume wherein one of the walls defines a door panel that is movable so as to define an opening into the volume. At least two hinges are mounted between the door or movable sidewall and a support plate, and enable displacement of the hinge axis along a line perpendicular to the closure plane of the opening. The support plate is located on a sidewall adjacent to the moveable sidewall or door, and is moveable between a first position and a second position thereby enabling the movable sidewall to shift to between (i) a closed and substantially sealed position corresponding to the first position of the support plate and (ii) a closed and substantially unsealed position corresponding to the second position of the support plate.
The lid in the first embodiment and the movable sidewall or door in the second embodiment are independently movable toward and away from the closure plane to engage or disengage the seal, and via their respective guides or hinges to clear the opening in a manner that does not interfere with the seal.